1.5.1 The Eden Basin Flashcards
Where is the Eden Drainage Basin?
The Eden Drainage Basin is in north-west England, between the mountains of the Lake District and the Pennines.
The river drains the north-east Lake District fells and the north-west Pennines.
Where is the source of the River Eden?
The Pennine hills in south Cumbria.
Where does the River Eden flow?
It flows north-west through Appleby-in-Westmorland and Carlisle.
Where is the mouth of the River Eden?
The Solway Firth at the Scottish Border.
Is the Eden Basin rural or urban?
Largely rural, although the River Eden does flow through Carlisle.
Vulnerability of Carlisle
The upland areas that drain into the River Eden experience extreme weather that can cause flooding downstream.
Carlisle is particularly vulnerable as it’s at the confluence of the Eden, Petteril and the Caldew, and is fairly low-lying.
How does farming affect the River Eden’s flood risk?
1) More intense farming has caused soils to be compacted, e.g. by heavy machinery or trampling by livestock. Between 2000 and 2009, there was a 30% increase in the number of cattle in the Eden Valley, meaning that much more land is likely to have been trampled.
2) Compaction of soils reduce infiltration, so surface runoff is higher. This means water levels in rivers rise quickly during heavy rainfall, increasing the risk of flooding.
3) Grazing in upland areas, e.g. hill farming of sheep, has also reduced the amount of vegetation that can intercept rainfall, resulting in more water reaching rivers.
How does construction affect the River Eden’s flood risk?
1) Although the majority of the Eden Basin is rural, built-up areas have increased. Many new housing estates have been built in and around Carlisle in recent years. For example, there are plans to develop a large ‘garden village’ to the south of the city, including up to 10,000 homes.
2) Surfaces in built-up areas tend to be impermeable, which reduces the size of infiltration flows and greatly increases the size and speed of surface runoff flows.
3) Some new developments in Carlisle have been built on floodplains. This has created a flood risk to property and has required the construction of flood defences to protect homes. Building on floodplains can cause flooding downstream as water that would naturally infiltrate on the floodplains flows downstream instead.
How does deforestation affect the River Eden’s flood risk?
1) Deforestation has taken place in the basin for thousands of years, e.g. to provide timber, and land for farming. Much of the original forest cover in the Eden Basin has now been removed, giving way to large areas of open grassland and heathland.
2) Trees increase infiltration and decrease runoff, so fewer trees means more runoff, flashier flood hydrographs and a greater risk of flooding.
How does climate change affect the River Eden’s flood risk?
1) Climate change is predicted to change rainfall patterns in the UK.
2) For example, parts of the western UK could get up to 35% more winter rainfall by 2080. Increased winter rainfall in the Eden Basin would increase runoff and flood risk.
Storm Desmond
In December 2015, Storm Desmond caused devastating flooding in Cumbria. Some of the worst flooding occurred in the Eden Basin.
In some areas of Cumbria, there was record rainfall. In Shap, 262.6mm of rain fall in 48 hours, between the 4th and 6th December. That’s 50mm more than the average rainfall for the whole of December.
Appleby and Carlisle were particularly badly affected. More than 2000 properties were flooded in Carlisle alone, leaving many people homeless.
